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Drought worsens: Colorado River flowing near 100-year low

Drought conditions continued to worsen along the Western Slope in the last week as temperatures rose, river flows reached near-record lows and peak snowmelt became a distant memory.

In the past week, Colorado River flows at the state line continued dropping. Streamflow is now recording at its 3rd percentile, meaning current flows are equal to or less than 97 percent of previous streamflow recordings for this time of year, according to a weekly drought briefing put out by the Colorado Climate Center at Colorado State University. Data for that stream gauge go back 61 years.

Third percentile is, “by definition ... very rare,” said Wendy Ryan, a research associate at the center, explaining that it essentially means the flows are the third-lowest they have been in the past 100 years in early June.

None of the stream gauges maintained by the U.S. Geological Survey in the Upper Colorado basin is recording above normal flows. Eighty-five percent of the gauges are below normal, while 65 percent are “much below normal or low” according to the CSU report.

“Unless they’re being impacted by reservoirs, the rivers are pretty low,” Ryan said.

For the month of May, much of the Western Slope and eastern Utah received less than 20 percent of average precipitation.

This, combined with a snowmelt that peaked much earlier than normal, has left soils in western Colorado and eastern Utah exceptionally dry, according to the climate center’s models.

Peak snowmelt occurred around early March this spring. It typically peaks around mid-April and last year did not come until late April.

That means significant snowpack is already gone below about 10,500 feet and soil that would normally be saturated by melting snow has been drying out in the above average temperatures, Ryan said.

“It’s just a model, so take it with a grain of salt,” she noted, but drier soils would mean farmers would have to irrigate more to maintain enough moisture for crops, meaning higher water demand could run up against lower water supply.